Patent EA-003315-B1 (EA)
Title: System for producing de-watered oil from an underground formation
Inventor: POLDERMAN HUGO GERARDUS
IPC: E21B43/40
Filed: 2000-12-14
Abstract: 1. System for producing de-watered oil from an underground formation to the surface, which system comprises -a production well extending downwardly from the surface and having an inlet below the surface; -a reception well penetrating the underground formation and capable of receiving well fluid therefrom, wherein the downstream part of the reception well comprises a substantially horizontal or inclined section for primary oil/water separation of the well fluid ; -a water discharge system having an upstream end that is capable of receiving during normal operation liquid from the lower region of the downstream part of the reception well; and -a secondary underground oil/water separator, characterised in that the secondary separator has an upstream end that is capable of receiving during normal operation liquid from the upper region of the downstream part of the reception well, the secondary separator having an outlet for de-watered oil that is in fluid communication with the inlet of the production well and an outlet for a water-enriched component that is in fluid communication with the water discharge system. 2. System according to claim 1, wherein the water discharge system comprises means to inject the liquid from the lower region and the water-enriched component into an underground formation. 3. System according to claim 1 or 2, further comprising a connection well, wherein the connection well has an inlet arranged to receive liquid from the lower region of the downstream part of the reception well, and an outlet in fluid communication with the water discharge system. 4. System according to claim 1 or 2, wherein the water discharge system comprises a water discharge well that is a branch of the reception well. 5. System according to claim 1 or 2, wherein the water discharge system comprises a water-discharge well of which the slope declines in the direction of fluid flow. 6. System according to any one of the claims 1-5, further comprising an additional reception well arranged to receive well fluid from the underground formation, wherein the downstream part of the additional reception well is in fluid communication with the downstream part of the reception well. 7. System according to any one of the claims 1-6, further comprising underground measurement equipment to measure a characteristic of a fluid at a certain position in the system. 8. System according to claim 7, wherein the characteristic is a concentration of a component in a fluid. 9. System according to claim 7, wherein the characteristic is the vertical level of an interface between layers of different components of the well fluid at a certain position in the system. 10. System according to any one of the claims 1-9, further comprising means to control the flow of a fluid at a certain position in the system. 11. System according to any one of the claims 7-9, wherein the system comprises means to control the flow of a fluid at a certain position in the system, and wherein data obtained from the underground measurement equipment is used as input for the means to control the flow of a fluid. 12. System according to any one of claims 1-11, wherein the secondary underground oil/water separator is selected from the group comprising a cyclone, a coalescer, or a static separator. 13. System according to claim 12, wherein the secondary separator is a static separator which is arranged in a separation chamber, and wherein the height of the separation chamber is larger than the thickness of the dispersion band that is formed therein under normal operation conditions. 14. System according to claim 13, wherein the static separator further comprises a flow distributor means, arranged to distribute at a predetermined vertical position the well fluid received through the separator's inlet over the cross-sectional area of the separation chamber. 15. System according to claim 13 or 14, wherein the static separator further comprises a level detector means and a flow control means in order to maintain during normal operation an interface between two liquid layers at a predetermined level. 16. System according to claim 13, wherein the static separator further comprises a stack of vertically spaced apart inclined plates, wherein between each pair of neighbouring plates a separation space is defined; -a substantially vertical inlet conduit communicating with the separator's upstream end, which inlet conduit traverses the stack of plates and is arranged to receive the well fluid at its lower end, and is provided with one or more outlets each of which opens into a separation space; -a substantially vertical oil collection channel having an oil outlet at its upper end communicating with the separator's outlet for de-watered oil, which oil collection channel has one or more oil inlets, each oil inlet being arranged to receive fluid from the uppermost region of a separation space, wherein at least the plate immediately below each oil inlet is provided with a vertically upward pointing baffle; and -a substantially vertical water collection channel having a water outlet at its lower end communicating with the separator's outlet for the water-enriched component, which oil collection channel has one or more water inlets, each water inlet being arranged to receive fluid from the lowermost region of a separation space, wherein at least the plate immediately above each water inlet is provided with a vertically downward pointing baffle. 17. System according to claim 16, wherein the inclined plates are substantially flat and arranged substantially parallel to each other, wherein each inclined plate is provided with a downward pointing baffle attached to the rim at the lower side of the inclined plate and an upward pointing baffle attached to the rim at the upper side of the inclined plate, wherein the remaining parts of the rim fit sealingly to the wall of the separation chamber, wherein the oil collection channel is formed by the space delimited by the upward pointing baffles and the wall, and wherein the water collection channel is formed by the space delimited by the downward pointing baffles and the wall. 18. System according to claim 16, wherein the inclined plates have substantially the form of funnels arranged substantially parallel to each other, wherein each funnel is provided with a central opening. 19. System according to any one of claims 13-18, wherein the separation chamber has a height/diameter ratio smaller than 6. 20. System according to any one of claims 1-19, wherein the secondary underground oil/water separator is arranged in an extended section of the production well.